Difference b//w div and class in CSS

Can you help me out with the differences b/w div and class in CSS. I mean they are both used for the same purpose? Using classes I can apply a particular effect to 1 of the 8 paras as in tne tutorial wheres in the case of div I can position the things wherever I want? I mean does the div attribute does not support color , font-weight ,etc? so that we could actually eliminate the use of classes altogether?